Conventionally, as a room temperature-curable organopolysiloxane composition capable of being cured to obtain an elastomer object (rubber-like elastic body) under a room temperature when coming into contact with water in the air (i.e. room temperature-curable silicone rubber composition), there have been known various types of them exhibiting various types of curing patterns. Particularly, those that are cured by releasing alcohols (dealcoholization type) share a feature of not producing unpleasant odors and a feature of not corroding metals. Therefore, such a type of composition is suitable for use in sealing, bonding and coating electric and electronic equipments.
Typical examples of the above type of composition include a composition consisting of a hydroxyl group-terminated polyorganosiloxane, alkoxysilane and an organic titanium compound; a composition consisting of an alkoxysilyl-terminated polyorganosiloxane, alkoxysilane and alkoxy titanium; a composition consisting of a silethylene group-containing alkoxysilyl-terminated linear polyorganosiloxane, alkoxysilane and alkoxy titanium; and a composition consisting of an alkoxy-α-silylester compound and a hydroxyl group-terminated polyorganosiloxane or alkoxy group-terminated polyorganosiloxane (Patent documents 1 to 4).
Although these compositions exhibit a certain degree of storage stability, water resistance and moisture resistance, they have not yet reached a satisfactory level. Moreover, these compositions have exhibited insufficient fast curabilities.
As mentioned above, polymers having reactive alkoxysilyl groups at their terminals are conventionally known. Since such polymers have their polymer terminal groups previously blocked by alkoxysilyl groups, their curabilities are hard to change (deteriorate) with time, and their storage stabilities are superior. Further, the workability (viscosity, thixotropy) of such polymers can be arbitrarily controlled, and these polymers are also capable of forming cross-linkages and elastomers by reaction with water in the air and exhibiting superior properties (hardness, tensile strength, elongation at break).
However, those of dealcoholization type have exhibited insufficient curabilities due to the fact that their reactivities with water in the air are lower than those of other known curing types such as deoxirnation type, deacetic acid type and deacetone type.
As a solution to such problem, studies have been conducted on functional groups (linking groups) adjacent to reactive alkoxy groups, and it has been reported that an α-alkoxysilylmethyl terminal group has a particularly high reactivity with water in the air (Patent document 5). However, there still exist disadvantages such as an insufficient curability; an adverse impact inflicted upon a durability by adjacent functional groups (linking groups); and a low restorability of a cured product.